Various catalysts have been proposed for use in the production of acrylonitrile by ammoxidation of propylene. In particular, substantial efforts have been made in the development of Mo--Bi base catalysts and a number of multi-component catalysts of this system have been proposed. Approaches directed to the refinement of these catalysts are described in many patents including: JP-B-No. 36-5870 (corresponding to U.S. Pat. No. 2,904,580) (the term "JP-B" as used herein means an "examined Japanese patent publication"), JP-B-No. 38-17967 (corresponding to U.S. Pat. No. 3,226,422), JP-B-No. 39-8512, JP-B-No. 45-35287, JP-A-48-47476 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-B-No. 51-33888 (corresponding to U.S. Pat. No. 4,503,001), JP-B-No. 57-65329, JP-B-No. 58-2232 (corresponding to U.S. Pat. No. 4,228,098), JP-B-No. 59-16817 (corresponding to U.S. Pat. No. 4,290,922), JP-B-No. 60-36812 (corresponding U.S. Pat. Nos. 4,377,534 and 4,162,234), JP-B-No. 61-26419 (corresponding to U.S. Pat. No. 4,443,556), and JP-B-No. 61-58462 (corresponding to U.S. Pat. No. 4,600,541).
The improved catalysts described in these prior patents are based on the combination of Mo, Bi and Fe and further contain catalyst components selected from expensive elements such as Co, rare earth elements and nobel metal elements. Because of the use of such expensive elements, these catalysts successfully provide fairly high yields of acrylonitrile. However, it has been difficult for Mo--Bi base catalysts to ensure adequately high acrylonitrile yields in the absence of those expensive catalyst components.